1. Field of the Invention
This invention relates to the art of linerless labels, methods of making same and to method of cleaning and using a thermal print head.
2. Background of the Invention
It is known to thermally print on plain paper or thermally coated paper tags and labels in a thermal printer. In many such printers, a tag or label web is moved while in contact with a stationary thermal print head. The print head remains clean enough in normal use to print a large number of tags or labels. An example of such a printer is found in U.S. Pat. No. 4,899,947 granted Feb. 13, 1990 to Ronald L. Fogle et al.
It has been found that a thermal print head used to print on release coated linerless webs causes streaking especially near the beginning of the printing operation. This streaking is caused by dirt, dust, debris, adhesive and the like that accumulates on the print head. This streaking tends to diminish with use of a linerless web having perforation cuts dividing the web into labels. However, until such time as the streaking diminishes to an acceptable level, streaked tags or labels result. This streaking is especially detrimental where parallel bars of a bar code are printed. For example, if a streak occurs at a place where the bar is printed, the resulting bar may be narrower than required and the adjacent space will then be correspondingly wider than required.
It is known to protect the tag or label web by providing a protective outer wrap as disclosed in U.S. Pat. No. 5,086,987 granted Feb. 11, 1992 to Roung-Min Shieh.
It is known that thermal print heads can be cleaned using special cleaning strips which are advanced between and in pressure contact with the print head and the platen.
It is also known to manually clean thermal print heads using cotton swabs containing alcohol.